Westfalenbad swimming centre in Hagen

Recreation pool beneath a convertible roof

Attractive leisure centre and, at the same time, a solution for high energy efficiency: at the Westfalenbad swimming pool complex in Hagen, Germany, the Dr. Krieger architecture firm based in Velbert has implemented a project that combines competitive sports and recreation facilities. This state-of-the-art swimming pool concept employs moving architectural elements that can turn areas of the covered installation into an outdoor pool. Demag drives provide for safe, reliable and precise movements of the roof structure.

Perfectly matching drive solutions from the Demag modular system

Reliable positioning of the travelling roof structure

Safe and reliable motions thanks to all-wheel drive

The project

Westfalenbad sets milestone

The Hagen municipal authority has created an outstanding swimming and leisure centre at the Westfalenbad complex. Covering an area of 8,000 square metres, the swimming pool centre combines competitive sports and a recreation facility under one roof. Besides a large sports area featuring a 50-metre pool, the Westfalenbad centre also includes generous recreation and wellness facilities. For the Dr. Krieger architecture firm from Velbert in the Rhineland, which is a leader in the construction of public swimming baths with 210 pools throughout Germany, the Westfalenbad complex was the largest swimming pool project so far.

Convertible roof for outdoor pool

One reason for the popularity of the new bathing centre is the moving roof section, which allows a part of the facility to be converted into an outdoor pool. In good weather, the convertible roof can be opened to provide visitors with all of the added fun of an outdoor pool in only a short time. The goal of a light-weight roof that is suitable for any weather was achieved with a combination of steel and a membrane foil. The travelling roof structure, which measures some 500 square metres in size, consists of a lattice of steel tubes, which is covered with a protective skin made of translucent ETFE foil.

The roof structure weighs 21,100 kg and is supported by 16 wheel blocks, which travel on two parallel rails. The travel wheels are made of spheroidal-graphite cast iron and have guide flanges on both sides. Also thanks to the self-lubricating effect of the encapsulated graphite, they provide for smooth and precise travel motions that are kind to the track. At a travel speed of 3 m/min, the leisure pool beneath the roof can be completely turned into an outdoor pool within eight minutes. The travelling structure is then parked above the flat roof of an adjacent part of the building. The drive system can also smoothly position the solution at up to wind force 5. During the winter, the closed roof can also bear an additional snow load of some 30,000 kg.

Reliable all-wheel drives

The Westfalenbad centre also includes another special feature: the travelling roof element is positioned at a slight angle, which involves an incline of four per cent that has to be managed. Smooth operation also has to be ensured even when the travel rails are wet.

The solution to meet these requirements is an all-wheel drive arrangement. 14 wheel blocks are driven direct by Demag offset geared motors. The design of the gearbox housing with a torque bracket and the solid involute-splined shaft ensure optimum transmission of the drive torque. An additional corrosion-resistant paint finish protects the installation from salt and chloride in the air. Angle rails attached to the steel superstructure, which are arranged to engage beneath the travel rails, prevent the roof from lifting off.

Perfect combination of components for an efficient system

The components used for the Demag drives, which consist of geared motors, wheels and frequency inverters, are perfectly matched. A Demag Dedrive Compact frequency inverter is responsible for controlling the drives to achieve particularly smooth and precise acceleration, braking and positioning. The inverter is arranged in a switchgear cabinet, which was integrated on the long side of the travelling roof structure. Power is supplied via an energy chain that runs parallel to the travel rail.